Anyone reading  medical research headlines in recent years has become aware of how charged the topic of gene therapy is. Recent clinical results treating certain types of blindness and adrenoleukodystrophy may leave people re-examining some of their thoughts and positions.

Leber’s congenital amaurosis is an inherited eye disease that appears shortly after birth. It’s caused by a recessive gene called RPE65 that controls production of an enzyme that recycles retinol. The result is sluggish pupil response with blindness or severe vision loss which until recently, doctors have been unable to treat. Doctors at both Children’s Hospital of Philadelphia and London’s Moorfield Eye Hospital have had substantial success treating this disease with gene therapy. The physicians surgically deliver modified adeno-associated virus (AAV) prepared by a Seattle company called Targeted Genetics behind the retina. AAV can affect both dividing and non-dividing cells with in the body and begins recoding the DNA for proper formation of the enzyme. One of the keys seems to be treating it at a young age, but the results of these trials particularly in the Philadelphia study are astonishing, and appear to be free of side effects according to Moorfield’s article in April 2008 New England Journal of Medicine article. Pretty astonishing.

The astonishing advancements don’t just stop there. Adrenoleukodystrophy, the subject of the 1992 film Lorenzo’s Oil, is another inherited disease. Instead of blindness adrenoleukodystrophy leads to progressive brain damage and death. Sufferers of adrenoleukodystrophy fail to transport a necessary enzyme for breaking down very-long chain fatty acids to where it’s needed. The eventual build up leads to damage of the adrenal glands and an inability of the body to myelinate nerves, leaving them unable to conduct impulses. The November 2009 publication of Science magazine has published the results of a French study in which two children with adrenoleukodystrophy have been successfully treated using gene therapy.

While both of these studies are in clinical trials and not yet available to the public they do offer hope of exciting advances in the near future. Additional studies not yet in clinical trials such as the University of Washington’s success in producing color vision in squirrel monkeys or the successful growth of bigger, stronger muscles in monkeys at Nationwide Children’s Hospital in  Columbus will undoubtedly lead research relating to color blindness of muscular dystrophy. Either way, the results of gene therapy are beginning to bear some of the fruits long talked about in the years of debates.

Moorfield Eye Hospital Information

Children’s Hospital of Philadelphia

Adrenoleukodystrophy Article

University of Washing Color Blindness Treatment